Historically, a large number of differing materials have been employed as building materials. For instance, the use of both wood and steel in the construction of commercial and residential buildings is well known. In general, selection between particular building materials, such as steel or wood, has been guided by a number of criteria. The criteria include cost and structural suitability and continuing efforts to balance these criteria have resulted in development of numerous alternative materials.
Recently, various types of plastic and composites have been developed as alternative building materials. These materials have been found to be both strong and durable. Additionally, many molding and forming techniques for plastics are well known. These molding and forming techniques allow plastic materials to be easily shaped into numerous structures including flat sheets and boards. Plastic materials may also be used in combination with numerous other materials to form composites, allowing the cost and other characteristics of the resulting products to be easily tailored to meet varying demands.
A prime consideration in the fabrication of plastic building materials is cost. In fact, market success of alternative building materials, such as plastics, is dependent on the cost effectiveness of these materials in relation to the more traditional materials that they are intended to replace. Cost effectiveness, is, in turn, dependent on the availability of low-cost fabrication methodologies and the use of low-cost raw materials.
In the past, fabrication of plastic structures, including those intended as building materials, has generally involved the use of a step-by-step process involving a number of distinct subsystems. In these processes, the output from each individual subsystem becomes the input for the next subsystem. As a result, each subsystem is repeatedly started and stopped and may experience idle periods as it waits for input from the preceding subsystem.
The non-continuous process typically employed to produce plastic structures includes a number of inherent disadvantages. One such disadvantage is high labor costs. Specifically, many of the individual subsystems may require supervision or operator intervention. Each subsystem that requires intervention or assistance generally increases the cost and unreliability of the fabrication process.
Another disadvantage associated with traditional methodologies is inefficiency caused by wasted material or energy. In greater detail, it may be appreciated that many of the subsystems employed in the production of plastic structures may have a start-up time during which the subsystem is brought up to its operating parameters. For example, a curing oven may have to reach a specific temperature before it can be effectively used. Subsystems of this type may waste energy or raw materials during the start-up period or have other undesirable side-effects such as increased air emissions. In general, inefficiencies of these types may result in higher operating costs and an associated increase in the cost of the final product.
Still another disadvantage typically associated with traditional manufacturing techniques for plastic structures is lack of output uniformity. Generally, it is highly advantageous if an industrial process may be conditioned to produce consistent results both within and between output batches. Consistency of this type allows the manufacturing process to be characterized and tuned to produce uniformly acceptable products. Unfortunately, manufacturing methodologies which operate in a step-by-step mode are often associated with inconsistent or varying output qualities. These inconsistencies are caused by the limited ability of the step-by-step process to continuously adapt to changing external conditions such as heat and humidity. Lack of consistency within batches and between batches may result in rejection of certain products and higher costs for the remaining products.
A second factor that contributes to the cost effectiveness of plastic structures used for building materials is the cost of input materials. It may be appreciated that in the case of plastic structures, the cost of the underlying plastic material may be quite high, especially for large structures that require high volumes of plastic. Cost of input materials has been especially important where traditional manufacturing techniques have been employed and the entire output product is fabricated from solid plastic.
One approach that has been successfully employed in an attempt to reduce the amount of raw input material used in the fabrication of plastic structures is the use of honeycomb or other hollow internal structure. This approach has yielded structures that are both strong and conserving of input materials. In practice, however, these structures are both complex and expensive to produce and require expensive adaptation and retooling for each different structure produced.
In light of the above, it is an object of the present invention to provide a system and a method for manufacturing plastic structures which operates as a continuous and on-going process. It is another object of the present invention to provide a system and a method for manufacturing plastic structures which features high operating efficiency both in terms of energy and materials consumed. Yet another object of the present invention is to provide a system and a method for manufacturing plastic structures which is adaptable to the production of numerous input material types and output shapes. Another object of the present invention is to provide a system and a method for manufacturing plastic structures which provides a high degree of output uniformity. Still another object of the present invention is to provide a system and a method for producing plastic structures that is not labor intensive. Still another object of the present invention is to provide a system and a method for manufacturing plastic structures which is relatively simple to use, is relatively easy to implement and is comparatively cost effective.